A gas treatment system for separating an acidic compound which generates an acid by dissolution in water from a gas containing the acidic compound such as carbon dioxide or hydrogen sulfide, for example, by using an alkaline treatment liquid such as an aqueous solution of an amine capable of absorbing the acidic compound has been well known (see, for example, Patent Document 1).
The gas treatment system disclosed in Patent Document 1 includes: an absorber for contacting the gas with the treatment liquid; and a regenerator for desorbing the acidic compound by heating the treatment liquid having absorbed the acidic compound such that the treatment liquid restores its ability to absorb the acidic compound.
In such a conventional gas treatment system, the treatment liquid having absorbed the acidic compound is heated to separate the acidic compound therefrom which is then collected, whereas the heated treatment liquid generates water vapor as well as a gas of the acidic compound (may be also referred to as “acidic compound gas”. Therefore, in the conventional gas treatment system, only the acid compound gas is collected through cooling the gas generated from the treatment liquid in the regenerator such that the water vapor is condensed, and thus condensed water is allowed to reflux into the regenerator, thereby preventing concentration of the treatment liquid. It is thus required that not only the treatment liquid having absorbed an acidic compound successively supplied to the regenerator, but also the condensed water is subjected to reheating, and consequently the conventional gas treatment system consumes a relatively large amount of energy.
In order to reduce the energy required for heating the treatment liquid having absorbed the acidic compound, the conventional gas treatment system performs heat exchange between the treatment liquid supplied from the absorber into the regenerator and the treatment liquid refluxing from the regenerator into the absorber.
Use of a treatment liquid has been also proposed which is capable of absorbing an acidic compound to undergo separation into a first phase portion having a relatively high content of the acidic compound and a second phase portion having a low content of the acid compound (see, for example, Patent Document 2).
In the gas treatment system disclosed in Patent Document 2, the treatment liquid having absorbed the acidic compound in the absorber is separated into the first phase portion and the second phase portion, and only the first phase portion is introduced to the regenerator, whereby the absolute quantity of the treatment liquid to be heated in the regenerator is reduced, leading to a further reduction in the amount of energy required for regenerating the treatment liquid.
However, the conventional gas treatment system utilizing the treatment liquid that can be separated into the first phase portion and the second phase portion still fails to sufficiently reduce the amount of energy required for separation of the acidic compound, and further energy savings have been awaited.